Drying method



De@ 24, 1929- M. U. BURNHAM ET AL D RYING METHOD @ein 24 1929 M. u. BURNHAM FI' AL DRYING METHOD Filed Feb. 20. 1925 3 Sheets-Sheet Del, 1929- M. u. Eurem-IAM ET Al.A 1,740,681

DRYING METHOD Filed Feb. 2o. 1925 3 sheets-sheet S 13 n l 13 l5 F I' S g'wua'nozs I1K3, M.U.BURNHAM GM. Mamme A. hxoma 53M l l w THE \R. ttoz new Patented Dec. 2 4, 1929.

UNITED STATES f PATENT! OFFICE '1 mouais U. B UgrNIIAM; or CINCINNATI, oII'Io, AND GEORGE zur. ARGABBITE AND ARTHUR A. .DIoNNE, or CHICAGO, ILLINOIS', AssIGNoRs To TIIE Army-FERGUSON CoMI'ANY, or CINCINNATI, omo, A CCRPCRATICN or oIIIo Y DRYING Application led February A method ofdrying leather which. will save time required when, asis now the common practice, the leather is permitted to dry naturally, either in an ordinary room or in 5 the open air outside the building, and which will be practicable for the drying 'of the leather on a large commercial scale and without injuring the structure of the leather, will in the nature of things introduce a very important economy in the leather art. This is especially true in the manufacture of shoes,

the production of which involves a multiplicity of different operations and must be v carried out on a large commercial scale in -order to be` economical and hence commercially successful. In the manufacture of shoes it is essential that the soles be in a wet condition, in order that they may be soft and pliable, when applied to the uppers, while subsequent operations require that .the soles be dry while these o erations are being performed. One step 1n the .manufacture of shoes therefore consists-i1? "the wetting of the soles prior to their application to theyy upper and anotherstep consists in the drying of the soles after they have-been so applied. While this drying operation has beenherein referred to as a step inthe manufacture of shoes it is as a matter of'fact now universally or substantially universally performed merely by permitting the soles to be dried naturally, the racks containing the .partially completed shoes being simply pushed' to a space or place provided or avail` able therefor in the factory and allowed to remain there until the operatives consider thev soles to be sufficiently dry for the subsequent operations. The time required for this drying operation varies, and is controlled in part by atmospheric conditions, a longer time being necessary, for example, in wet weather than in dry weather. `The variation in time, in fact, is very considerable, ranging from about three days to abouttwelve days. During all of this time the lastsrare' in partially formed shoes. V

It, therefore, follows (l) that a large extent ofzfloor space must be devoted to the storage of the shoes while undergoing the natural drying operation; (2) that a. very METHOD 20, 1925. Serial N0. 10,578.

large number of racks are required for the transfer of the shoes to and away from the drying room or space and for the storage of the shoes while being dried, since the racks retain the shoes during the entire drying period; (3) that considerable manual labor is involved in and considerable aisle space required for, the transfer of the racks to the drying room or space and from the drying room or spaceto the machine where the next operation in the manufacture of the shoes is performed; (4) that a very large supply of lasts is required owing to the slow turnover inthe use thereof, since each last, as already stated, necessarily remains in the shoe being formed upon it during the entire drying operation as well as during the previous operations and several of the su sequent operations. i Notwithstanding these well recognized disadvantages the drying of the soles naturally has been retained as the common practice owingto the fact that artificial drying has not been attended with much success owing \to the peculiarity of leather which if sudidenly deprived of moisture is broken down "in structure, becomes britt e yand loses` its tensile strength, so that it cracks when bent. A shoe having a sole ofsuch nature would give no service.

Although more particularly intended for the drying of the soles of shoes in the process of manufacture of the shoes, it is not our intention to limit its application to the drying of such articles, since we realize that it may be usefully employed in the drying of many things, especially leather products of different kinds. For example, it may be very usefully employed to dry hides as they come -from the tanning baths. 90

A most important purpose of this invention, therefore, is to eliminate the disadvantages incident to the natural drying of leather without injuring the structure of the leather as compared with that dried naturally under most favorable'conditions. To this end the invention broadly comprehends a process by -Which the leather undergoing treatment is subjected progressively to rapidly iowing currents of heated humidilied air and heated 100 substantially dry air artificially produced and whose speed of flow, humidity and temperatures are controllable in accordance with the requirements of the particular leather lunder treatment, whereby the leatherthus subjected to these controlled atmospheric conditions is dried from the inside outward in a comparatively short space of time.

The invention further comprehends (l) The passage of the articles being dried through a rapidly flowing current of heated and humidiiied air having what may be referred to as zones of different temperatures, whereof the temperature of the heated humidified air is lower at the place where the articles are first subjected to this step of the process and also at the place Where this step is completed than in the intermediate zone;

(2) rl.`he passage of said articles then progressively through a rapidly flowing current of substantially dry heated air similarly having what may be referred to as zones of different temperatures, the temperature of this ai being higher at the middle than at either en (3) The admission of the humidified and heated air at a plurality of different places with relation to the travel of the articles under treatment through thev zone or zones of such air; A

(4) Similarly the admission of the substantially dry heated Aair at a plurality of different places with relation to the travel of the articles under treatment through the zone or zones of substantially dried air;

(5) The retempering of the leather by subjecting it to the action of humified air immediately at the conclusion of its travel through the zone or zonesof substantially dry heated air.

No arbitrary rule as to the percentage of humidity, the degrees of temperature or the velocity of the airs, or the length of time during which the leather is subjected to these airs can be laid down, as these depend upon varlable conditions. Recognizing, therev fore, that the humidity, temperature, ve-

locity of the airs and the length of time to whlch the leather is subjected thereto in carrying the process into practice will be dependent upon variable conditions and reserving to ourselves the right to employ any such which are capable of giving satisfactory results, we would state that'in the practicable application of the process in the manufacture of shoes upon a very large commercial scale perfect results have 'been secured from the following procedure which is being practiced, to wit:

The shoes are first passed through a current of air whose .temperature varies in different portions of its length being approximately 80-85 degrees F. at its ends where the shoes enter and leave the current and approximately 90-95 degrees F. at the parts of the sufficient to dry the leather from the inside,

leaving it in Vsuch shape that remaining moisture can be driven olf in a dry temperature without 'injury to the leather. The

next step consists inV passing the shoes through a currentof substantially dry air increasing in temperature from about 120 or 125 'degrees F. at its end Where the shoes enter it to about 140-145 degrees F. and then decreasing to 120-125 degrees F. at its end where the shoes leave it, and having a velocity of from about 5000 to 800() cubic feet per minute. The velocity of the airs should be determined in accordance with the condition of the leather and the humidity and temperature of the air. The duration oftime of the second step usually is about one and onehalf hours. The times herein mentioned are especially applicable to welt shoes, nailed shoes requiring less time.

Experience has demonstrated that the drying of the shoes by this process has resulted in a product which is equal in all respects to those dried naturally under most favorable conditions, and in fact is attended with far less danger than when the shoes are dried naturally in steam heated rooms, the dry air of which frequently breaks down the structure of the leather. The-process further reduces the time required from many days to only a few hours, the drying of the shoes by natural atmospheric conditions or in ordinary heated rooms, as at present, requiring from about three days to about twelve days, as already stated.

It has been found to be desirable in practice to subject the shoes to humidiiied air while they are passing through the zone of heated dry air and after they have passed the place of highest temperature thereof. This moistens the soles and uppers to a sufticient extent to re-temper the leather and thereby place them in better condition for subsequent operations.

In the carrying out of the process on a large commercial scale the leather under treatment is moved progressively through suitable treating chambers-into which the heated humidiied and heated substantially dry airs are introduced at different places in the lengths of chambers, from outside sources, respectively; This provides a safeguard against over-saturation of the airs by moisture extracted from the leather, and in co-operation with the rapid change of the airs in the treating chambers causes the effective Withdrawal of the moisture from the leather in a minimum of time and Without conveyor Y, Y extending continuously past a number of operatives stations, marked Operat1ves, and serving to transfer the racks X from operatlve to operative and to the elevating conveyor Y2 which carries the 23 4racks into the receiving end of the leather conditioning chamber A and delivers the same to the conveyor B which traverses said chamber. Fig. 2 shows one side of the section Y which leads to the elevating section .25 (the other side of said section bein omitted for lack of space to show it) and a so shows a lowering conveyor Y3 which extends from the rack discharging end of the tunnel A and conducts said racks with the conditioned and partially completed shoes downward toV n 'ajconveyorg whose end is indicated at Y, and along which other operatives are stationed. The conveyors employed are of any nature suitable for use in this process/un an application for Letters Patent of the `United States filed by us on June 7, 1924, and numbered, serially, 718,661, we have shown, described. and claimed a conveyor forms the subject of the instant applicationl for patent. Ifon.the other hand, the leather is in theform of hides asthey come from the tanning vat, for example, the conveyor or conveyors may be of a suitable nature adapted to carry the hides in suspended position through theI treating chambery or chambers. VAn apparatus particularly .well adapted to the carrying of this process intqpractical effect, is shown in the accompanying-drawmgs. This apparatus embodies two chamare subwhich are arranged outside of and are suit' ably connected to, the chambers, and suitable. means cooperating withr the air heatmg` and humidifying means are provided to control the volume, speed of travel and temfor transferring the racks from operative to y bers through which the articles to be dried' peratures of the airs, in accordance with requirements. Two styles of conveyors traversing the chambers are illustrated, one being exemplary of a conveyor which is preferred when the articleto be dried is of a kind which should be carried by a traveling bed upon which it rests and the other eX- emplary of a form which should be used when the article to be dried is of a kind which should be suspended while being dried. This apparatushas been made the subject of an application for patent filed in the United States Patent Oiice of even date herewith and numbered serially 10,577.

In the drawings illustrating the said apparatus, and in which drawings like characters of referencev denote corresponding parts in the several figures:-

Fig. 1 is a side elevation.

Fig. 2 is a plan view. l

Figs. 3, 3A and 3B are horizontal sectional views conjointly illustrating the apparatus; Fig. 3 being a view of the end of the apparatus at which the articles enter and leave the drier; Fig. 3A- a view of the intermediate portion of the drier; and Fig. 3B a view of lthe end opposite the end shown in Fig. 3.

Fig. 4 is a cross sectional view on a larger stale than the preceding figures, taken through one of the tunnels andthe corresponding conduit through which it receives the humiditied or substantially dry air, as the case may be. Y

Fig. 5 'is a view similar to'Fig. 4 but showing a style of conveyor preferred when the articles to be-dried are of a nature such that they should be .carried through the drier in suspended condition.

A and A' designate two chambers, in the form of tunnels. These two tunnels may be of any suitable length and may be correlated in any manner which 'will enable the articles to be Asubjected to the various steps of the drying treatment in their travel first through one tunnel and then through the other. A very desirable arrangement is that illustrated in the drawings, which show them arranged side by side and in substantial parallelism with each other and with the entrance to the tunnel A and the exit from the tunnel'A -at the same end of the apparatus and said tunnels connected with each other near said end by a transversev duct A2 and having their oposite ends connected by a transverse chamer A-. It would not, however, be a departure from the spirit of the invention to arl range the tunnels in other positions relatively to'each other-'but the illustrated arrangement is preferred because of its comparative compactness. 1

The articles to be dried are moved at a suitable speed throughout the lengths of both tunnels A, A', also within the chamber A from the dischar ing end of tunnel A to the receiving end o tunnel A', by conveying tunnels A and'A and chamber A, respec-- tively, and gravity conveyor sections b and b', respectively arranged to transfer the articles from the discharging end of conveyor` B to theiconveyor B and from said'conveyor B to the receiving end of convevor B. Each of the illustrated endless trave ing conveyors is ofr that known type comprising endless side chains -10 which traverse suitable sprockets at the ends of the conveyors and are provided with rollers 11 which traverse upper tracks 12 and lower tracks 13 and with transversely extending rollers 14 which are arranged between the chains and connected thereto and conjointly form the bed of the conveyor. The tracks 11 and 12 are suitably supported above the bottom 15 of the tunnel as by suitably connected and braced upright frame-members 16 carried by the bottom wall 15 of the tunnel. This construction of conveyor is simple and practicable,since it provides a strong and yet simple traveling Support for the racks X which carry the shoes undergoing the drying operation, and will not sag under the weight of said racks and shoes and may be operated with a minimum of power. It, of course, will be understood that power is applied, as is usual, to the i sprockets at one end of each conveyor and that the sprockets at the other end of each conveyor are idlers and in practice are provided with suitable means to take-up slack in the conveyor. Since power and take-up means are common in the conveyor art and their application to this type of conveyor is l well understood it is unnecessary particularly to illustrate the same as a part of this mecha msm.

It will be understood that the particular conveyor used will be of the style and character most appropriate forthe particular thing being dried. For example, instead of using the particular conveyor set forth, or any conveyor having a traveling bed to support the article being dried, it will be found desirable when hides or the like are the articles being dried to use a conveyor, marked B", of the type from which the articles being driedmay be suspended, or may depend, as indicated in Fig. 5. This conveyor comprises endless traveling chains 30 and suitable means or members, indicated at 31,*supported thereby and in turn supporting the hides X. In

no respect other than with relation to the same regardless of the particular article being dried.

A suitable air-heating vand humidifying means C is arranged outside the tunnel A and about midway the length thereof and a suitable air heating means C similarly is arranged outside of and about midway the length of the tunnel A. The means C may be of any construction or type and capacity which will supply Inoistened air in suiicient volume and at the temperature required to subject the articles traversing the tunnel A to the treatment predetermined for said articles in said tunnel, and the means C similarly is of any suitable construction and capacity to supply substantially dry air in sufficient quantity and at the required temperature for the treatment predetermined for the articles in their travel through the tunnel A. Means suitable for these several purposes are known and sinceA a particular constructionthereof forms no part of this invention it is unnecessary `to illustrate orafurther refer to any details of the source of heated huinidiiied air or of the source of dry heated air as a part of this application. Mention, however, may

` be made of the fact that the source of humidia conduit E at about the longitudinal center l of the latter. This conduit extends lengthwise of the tunnel A and from it the said tunnel receives the heated humidiiied air supplied by the 'means C. This air lflows in oppQsite directions within the conduit from the inlet to said, tunnel, the inlet portion of the conduit being provided with diverging wall members such as those shown-at 21 in Figul to induce such flow, and passes from the conduit into the tunnel A through ducts 20 which are. suitably spaced along vthe lengths of the conduit and tunnel. The sections of the conduit from the inlet to the firstI duct on each side thereof, and from each of said ducts to the next, are respectively of lesser diameter, to compensate for the lesser volumes of the air in these sections and in order that the speed of the flowof air may be maintained. To control the supply of this air from the conduit to the tunnel at the various placesl at which the air is introduced into the tunnel, cach section of the .conduit is provided with a suitable manually operable valve or damper 22. These dampers or valves are preferably located within the ducts 20, respectively.

The heated dry air is similarly discharged from the heater C under pressure from a suitable fan D into a conduit E. This conduit is like the conduit E and bears the same relation to the tunnel A that the conduit E does to the tunnel A. Its dampers or valves are marked 22 and the spaced ducts through which itV has communication with the tun! and in consequence a rapid change of the -air therein. The fan F is preferably connected to the chamber A and in such operative relation to said chamber and to the tunnels A, A that it will drawthe air from the chamber A and hence induce a rapid.

liow of the air in the tunnels A, A toward said chamber. A suitable damper or valve, as indicated at 23, is provided to control the air outlet from the casing 24 which contains this fan. The fan F is preferably connected to the air outlet end of the tunnel A to draw the air toward said end, and is in operative relationship with the tunnel A through the duct A2 connecting the tunnels with each other at this end of the apparatus.

Therefore, it will be seen that the pressure fans D, D and suction fans F, F cooperate with each other in creating a rapid flow of constantly changing air in the tunnels A, A and chamber A and duct A2. These fans, together with provision whereby the air may be controllably introduced into the tunnels at different places in the lengths of the latter enables the operator to regulate the volume, speed of travel and temperatures of the humidiied air in different parts of the tunnel A and of the dry heated air in different parts of, the tunnel A', and to avoid oversaturation of the air. A

A re-tempering of the dried leather to make the same suliciently flexible for subsequent operations is made possible by the apparatus illustrated, the drawing showing a duct 30 (Fig. 2) extending to the tunnel A from the conduit E which carries the humidiied air. This duct 30 communicates with the tunnel A at a point near the discharge end of the latter. y

Each of these tunnels is preferably provided along its length with a series of doors G to afford access to its interior for testingnor tother purposes.

In practice, and as indicated generally or conventionally in Fig. 1 of the drawing suitable means are provided at appropriate places to show the condition with respect to speed .of travel, temperature andI humidity of the air in the tunnels and it is apparent that if i considered to be desirable means (as indicated by the parts marked Thermostat in Fig. l)

may be provided to automatically -control volume, speed of travel,temperature and/or humidity in accordance with a predetermined setting ofwsaid means. Y

Having thus described the'process and a suitable means for carrying the same into practice, what We believe to be new and claim as our invention, is

1. A drying process which comprehends the creation within a drier of a zone of rapidly i flowing heated humidiied air whose temperature at both ends of the zone is lower than that between said ends and the movement of the article to be dried through said zone.

2. A drying process which comprehends the creation within a drier of a zone of rapidly flowing heated substantially dry air whose temperature at both ends of the zone is lower than that between said ends and the movement of the article to be dried through said zone.

3. A drying process which comprehends the creation within a drier of a zone of rapidly 'flowing heated humidied air whose temperature at both ends of the zone is lowerl than that between said ends, the movement of the article to be dried through said zone, and the subjecting of the article thus treated to the action of a current of heated substantially dry air.

4. A drying process which comprehends the creation Within a drier of a zone of rapidly fiowing heated substantially dry air whose temperature at both ends of the zone is lower than that between said ends, andthe subjecting of the article to be dried to a humid atmosphere and thereafter to the eiect thereon of the said Zone of substantially dry airwhile the article is traversing said zone.c

5. A drying process which comprehends the Isubjection of the article to be dried to a humid atmosphere of increasing and decreasing temperature and then to a heated substan tially dry atmosphere.

6. A drying process which comprehends the subjection of the article to be dried to a humid atmosphere and then to a heated substantially dry atmosphere of increasing andl decreasing temperature.

7. A drying process which comprehends the subjection of the article to be dried to a humid atmosphere of increasing and decreasing temperature and then to a heated substantially dry atmosphere of increasing and decreasing temperature. y

8. A drying process which comprehends the creation Within a drier of a zone of rapidly iowing'heated humidied air whose temperature is lower at the ends of the zone than at the intermediate part thereof and a separate zone of heated substantially dry air whose temperature at the ends of the zone is lower thanthat at the intermediate part thereof, and the movement of the article tobe dried through these zones, successively.

9. A drying process which comprehends the heating and humidifying of air to substantially predetermined degrees of heat and humidity, the heating lwithout humidification of air to a substantially predetermined degree of heat and' dryness, the introduction of the pre- A hea-ted and prehumidilied air into a drying the drying chamber, and t-he movement of the article to be treated progressively through the zones of heated humidihed air and heated substantially dry air thus created in lthe drier.

. 10. A leather dryingl process which comthe-creation within a drier of a zone of rapidly flowing heated humidied air, a zone of rapidly flowin substantially dry air and a second zone 0% rapidly flowing heated humidilied air, and the movement of the article to be dried through these, zones, successively.

14'. The process of drying or conditioning partially completed shoes, forming steps in the manufacture .of the shoes, said process the conveyance of the shoes comprehendin path one portion of which is along a deline through a covered chamber, the introductionv preh ends the introduction into a first drying'into said chamber of a desiccating current of Zone of a rapidly flowing current of moderately preheated and prehumidiied fluid having a regulated speed of flow within said portion of the drier and regulated also as to its l volume, heat and humidity, and also compre- -mately 70-75degrees and a temperature of air which has been previously humidifed and moderately heated, vand a later portion of which path is through a second covered chamber supplied with a current of heated air having less humidity and higher temperabends the introduction into a second drying ture than the air in the first mentioned chamzone of a rapidly owing current of preheated ber, together with the regulation of the temsubstantially dry air similarly regulatedwith perature, humidity, volume and speed of flow respect to its speed of flow within the drier of the conditioning airs to effect a partial dryand toits volume and temperature, the venting of the fluid from both portions of the drier at a speed which induces arapid flow ing without sealing the pores of the leather in the first mentioned chamber and a further drying in the second chamber without danger thereof within the drier, and the movement @of breaking .down the structure of the leather,

of the leather to be dried progressively through these zones. f

1l. A leather dryingprocess which comprehends the introduction into one portion of a drier of air having a humidity of approxiapproximately 90-95 degreesF., the introduction into another portion of the drier of substantially dry air having a `temperature of 'approximately 140-145 d-egrees F., the inducing of a rap-id flow of these airs within the drier and the movement of the article to be dried progressively through the zones of rapidly flowing air thus created in the different portion of the drier.

12. A leather drying process which comprehends the introduction into one portion of-a and approximately 90-95-degre'es F. at a place intermediate s aid ends; and also comprehends the introduction into,l another portion of the drier, at a place intermediate the length thereof, of a. substantially dry air, under conditions which will induce within said portion, a .rapid flow of said air and` temperatures of from about 120425 degrees F. at the ends of said portion of the drier and about 140,-145 degrees F. intermediate-said ends; and the movement of the article to be dried progressively through the zones of rapidly flowing air thus v created in the dierent portions of the drier.

v 13. A drying process which comprehends 15. The process of drying or conditioning partially completed shoes, forming steps in the manufacture of the shoes, which comprehends the conveyance of the shoes along a defined path, successive portions of which are through covered chambers, respectively, the introduction into the, first of said chambers at different' places along its length of relatively regulated desiccating currents of prehumidiied and-preheated air and the introduction into the other of said chambers at different places along its length of relatively regulated desiccat'ng currents of preheated air having less hlinidity than that supplied to the first-mentioned chamber.

16. The process of drying or conditioning partially completed shoes, forming steps in the manufacture of the'shoes, which comprehends the lconveyance of theshoes along a defined path, one portion of which is through a covered chamber supplied at different places along its length with currents of rapidly flowing prehumidified and preheated air and another portion of which pathis supplied at different places along its length with currents of preheated air having less humidity than that supplied to the first-mentioned chamber, together with regulation of the air in the irst-mentioned chamber'to cause the temperature to be lower at both ends of the chamber than at the intermediate portion thereof and similarly thev regulation of the air in the second-mentioned chamber to cause the temperature to be lower at both ends than at the'middle of-the chamber.

1.7. The process of drying or conditioning 13o the manufacture of thelshoes, said process comprehending the conveyance of the par'- 4tially'completed shoes along a defined path one portion of which is through a covered chamber supplied with a flowing body ofair which contains a predetermined percentage of moisture ald has a temperature above that of the atmosphere and below that at which the animal matter'in the wet leather will be burned, to effect a partial drying of the leather without sealing the pores thereof, and a later portion of which path is through acovered chamber supplied with a flowing body of air having less humidity than the air in the first cham-ber to further deprive the leather of its contained moisture.

18. The process of drying or conditioning partially completed shoes, forming stepsv in the manufacture of the shoes, said process comprehending the conveyance of the partially completed shoes along a defined path one portion of which is through a rst covered chamber supplied with a flowing body of air-which contains a predetermined percentage of moisture and has atemperature above that of the atmosphere and below that at which the animal matter inthe wet leather will be burned, toeffect a partial drying of the leather without sealing the pores thereof and a later portion of which path is through arcovered chamber supplied with a flowing body of air having less humidity and higher temperature than the air in the first chamber to further deprive the leather of its contained moisture.

. 19. rlhe process of drying `orvconditioning i partially completed shoes, forming steps in the manufacture of the shoes, said process comprehending the conveyance of the previously wetted partially completed shoes along a defined path, one portion of'which is through a first covered chamber supplied with allowing'bodyl of humid air whose temperature and humidity are regulated to create a drying zone the atmospheric conditions in which will be characterized by a moderate heat at the entrance end of the zone and by a somewhat greater heat further along in the zone end at all places in the zone will be such that the animal matter in the leather will not be burned and the pores of the leather will not be closed; anda later portion of which path is through a second covered'cham- A(il) ber supplied with a flowing body of air whose temperature and humidity are regulated to create an atmospheric condition by which moisture remaining in the shoes after the latter have passed through the first zone is removed and the shoes left in condition for further manipulative steps.

20. The process herein described of drying orconditioning partially completed shoes, forming steps in the manufacture of the shoes, which comprehends Athe .conveyance of the wetted shoes along a defined course, successive portions of which are through a first drying chamber and a second drying chamber, the subjection of the shoes While passing through the first chamber to the action of a desiccating current of air which has been pretreated in respect of temperature and humidity, the regulation of said air to cause a predetermined increase in temperature and decrease in humidity from the place at which the shoes enter the chamber toward the place at which they leave said chamber, calculated to partially dry the leather without burning the animal matter therein or closing the pores thereof, and then the removal ofthe remaining moisture by the subjection of the-shoes while passing through the second chamber to the action thereon of a second desiccating current of preheated air of increasing temperature from the entrance end of the chamber toward the discharge end thereof.

21. The process of drying or conditioning partially completed shoes which comprehends the conveyance of the wetted and partially completed shoes along a defined path and their subjection while traversing said path to the effects of owing bodies of air in moisture transferring relationship with the shoes and which bodies of air are regulated in respect of heat and humidity to'form atmospheric conditions such that the shoes pass through a drying zone characterized by a humid condition, and by a moderate temperature at the place where the shoes enter the zone and by a substantially gradual increase in temperature to a place further along in said los partially completed shoes which compre-` hends the conveyance of the wetted and partially completed shoes along a defined path and their subjection while traversing sai path to the effects of flowing bodies of air in moisture transferring relationship with the shoes and which bodies of air are regulated in respect of heat and humidity to form atmospheric conditions such that the shoes pass through a drying zone characterized by a humid condition and by moderate temperature at the places where the shoes enter and leave said humid zone and by a higher temperature of substantially gradual increasing and decreasing nature between said places, and thereafter pass through a second drying zone of substantially dry air whose temperature is higher than that of the `lair in the first zone and increases substantially graduallv from the place at which the shoes enter the zone to a place further along in thezone and decreases substantially graduall from the latter place to the shoe eXit end o the zone. j 23. The process of drying or conditioning partially completed shoes, forming steps inr the manufacture of the shoes, said process or conditioning partially completed shoes,

whose soles have been wet as a step in the manufacture ofthe shoes and which drying comprehending the conveyance of the preor conditioning process forms additional steps viously wetted partially comp/leted shoes` along a defined path and subjecting such shoes while moving along a predetermined part of such path to the'action thereon of a desic'cating lcurrent of air having a predetermined percentage of humidity calculated to remove moisture from the-shoes without closing the surface pores thereof, and thereafter subjecting the same shoes,y while traversing another part of their path to the action of a second desiccating current ofair characterized by lesser humidity and higher temperature than the' temperature and humidity of the current to which the shoes were previously subjected.

24. The rocess herein described of drying or condltioning partially complete-d shoes, forming steps in the -manufa'cture of the shoes, which comprehends'the conveyanceI of I the shoes along a defined path from operative to operative and portions of which path are lthrough covered chambers respectively containing rapidly owing bodies of desiccating airs of which that in the chamber first traversed by the previously wetted shoes contains percentages of heat and humidity predetermined to cause a partial drying of the shoes without burning the animal matter contained inthe leather and without sealing the pores of the leather, and theair inthe chamber later traversed by the shoes is of lesser humidity' and higher temperature than that in the first mentioned chamber and deprives the shoes of contained moisture.

25 The process herein'desoribed of drying or conditioning the soles of partially completed shoes while the s hoes are in motion from an operativewho performs one operation to an operative who performs another operation in the manufacture of the shoes, said process forming steps in the manufac-VA ture of the shoes, and including the creation within an appropriate drying chamber of a rapidly flowing current of preheated. and prehumidified air and the creation within another appropriate drying chamber of a rapidin the manufacture of the shoes and comprehends the conveyance of the shoes along a defined path from operative to operative and successive portions of which path are through a first and a second covered chamber, the subjection of a first flowing body of air to heating and humidifying agencies to raise its temperature -and its humidity content-to predetermined percentages calculated to be below that at which wet leather to be in contact therewith will be burned or will have its pores closed, the causing of a rapid fiow of this preheated and prehumidifed air through the chamber first traversed by the previously wetted shoes, the heating without humidi- Iication of a flowing body of air to a higher temperature than that of the first mentioned body of air, the causing of a rapid iow of this preheated non-humidifed body of air through the second covered chamber, and the regulation of the speed of movement of the, shoes within the chambers to cause their retention in contact with said first body of air for-a suicient time to partially dry and prepare them for the action of the .higher and l drier second body of air without injuryfbythe latter and in contact with thesecond body of air for a sufficient ytime to substantially MORRIS U. BURNHAM. GEORGE M. ARGABRITE; ARTHUR A. .DioNNn ly iowing .current of air having higher temv perature and less humidity than the air in the firstl mentioned chamber z. the movement of said partially completedshoes through said the shoes remain in each of the same to cause la. drying ofthe soles without burning and without sealing the pores of the leather by partially drying them in a moderately heated 

